Hello, DeBerryAdminSolutions.
 

I'm so glad to hear that you were able to find and share with us a workaround for sorting customers by last name without having the last name show up first on the invoice. Please know that your opinions and ideas matter to us to help improve your experience in QuickBooks Online (QBO).
 

Feel free to tag me in the comment section if you have any other information or concerns with managing customers in QuickBooks. I'll be happy to assist you. Stay safe, and have a prosperous business!